The effect of thermocycling on five adhesive luting cements

The importance of bond strengths between dental luting cements and dental restorative materials has become increasingly important as a result of the adhesive technologies that have been developed over recent years. This study investigated the effect on tensile bond strength at the metal to cement interface for a semiprecious alloy for different prepared surfaces, cements and ageing regimes. At 24 h following preparation, silicoating and C & B Metabond appear to have distinct advantages in terms of interfacial bond strength, which was also noted after storage for 7 days in buffered saline. After thermocycling only silicoating conferred greater interfacial tensile strength, and any advantage that the 4-Methacryloxyethyltrimellitic anhydride (4-META) chemistry may have had at 24 h was no longer apparent. The poorest performing cement regardless of the ageing regime was Aquacem, although in relative terms its performance improved after 24 h. This preliminary investigation indicated that in vitro environmental ageing including thermocycling erodes the claimed advantages of some more novel dental adhesives. This may have important clinical consequences in their usage, although it must be appreciated that current thermocycling methodology may not be an accurate predictor of in vivo performance.